1. Field of the Invention
The invention relates to techniques for packaging solid state image sensors.
2. Description of the Related Art
Packaging of optical sensor integrated circuits has generally been accomplished using standard techniques for packaging integrated circuit dies. The integrated circuit die is placed in a cavity in a plastic or ceramic housing; wire bonding is typically used to make electrical connections to the die; and a window is placed (or molded) over the cavity. When placed in an optical system, the location and attitude of the package may readily be determined, but this is of little assistance in determining the location and attitude of the die (the top surface of the die should typically be coincident with the focal plane of the optical system) because package tolerances lack the requisite precision and because the package does not provide a reference surface positioned accurately with respect to the die. Each packaged sensor die must be separately focused to its optical assembly. Separate focusing is an expensive and error-prone process.